Bernard Hedges (John Alderton) is a newly-qualified, idealistic young teacher working in a tough South London school, Fenn Street Secondary Modern.

As the newest member of staff, he 'draws the short straw' when he's put in charge of Class 5C, the most 'difficult' group of children in the school.

The final series saw major cast changes. John Alderton only appeared in two episodes, then his character left for a year's 'study leave'. The main 'pupils' had moved on to the spinoff programme, The Fenn Street Gang and were replaced by new characters. John Esmonde and Bob Larbey passed the writing on to others.